In easy terms, why are rainbows curved?

Question

I would like to explain why rainbows appear in a bow shape to a primary school aged child.

Answer 1

The easiest explanation (for a kid) is that light, is not just white, but a bunch of different colors. Show them a prism and they'll see that easily. ALSO, each color has a different wavelength and will "appear" to human eyes at a different distance AND level in the sky. That is why it seems to be curved. Reddish waves will always be more visible LOWER in the atmosphere, whereas bluish waves, in the upper atmosphere (one reason our sky looks blue).

If rain, which acts like a prism, creates a HUGE rainbow, breaks up the "white" light, then the different wavelengths cause a rainbow effect (some are higher, some lower).

You might also point out that rainbows can ONLY (usually) be seen if you are standing between the sun & and the rainbow! So, if the sun is in the west, the rainbow will be in the east.

Other natural causes should be given, such as waterfalls, or even the spray from a garden hose, which is a very good way to illustrate this phenomenon of the "breaking up of light"!

Kudos to you for going the distance to make learning easier and fun for kids!

Answer 2

It has nothing to do with the curvature of the earth or roundness of the sun. It is because the water vapor is acting as a reflecting lens. If you have ever taken a magnifying glass and made a hot spot, you will understand this better. The only difference is that the magnifying glass concentrates the light towards a point (THE FOCUS) through transmission (bending the light as it passes through the lens) whereas a rainbow occurs when the light is concentrated to a focus by reflection (this is why the sun is behind you when you se a rainbow). We only see a bow (an arc) because we are on the surface of the earth and about half of the lens is blocked by the earth`s surface.

Sometimes you can see a ring around the sun or the moon, which is more or less the same process but none of the lens is blocked so we see a ring instead of an arc.

I suspect you already understand that the colors appear because the different light wavelengths bend or bounce at slightly different angles, separating the colors out of the white light source.

Answer 3

The main reason for the formation of a rainbow is the refraction and reflection of the sun's rays as they fall on drops of rain.
As a ray passes into a drop of rain,the water acts as a tiny prism.The ray is bent or refracted as it enters the drop and is separated into different colours.Then it strikes the inner surface of the drop and gets further refracted or reflected and dispersed.Seven colours are thus formed and we rarely see not more than three or four colours due the blending of the adjacent colours.Each colour is formed by rays that reach the eye at a certain angle.This value is 42 degrees for a primary rainbow.The higher the sun,the lower the bow.
According to simple geometrical principles,all the rain drops which lie at this particular angle(or which subtend this particular angle at the obsever's eye)and in a direction opposite to the sun,lie in the form of a full circle or a part of it(arc).Even if there are enough drops to form a full circle ,to an obsever on the earth's surface,it will look like an arc only as it is limited by the horizon.
When the sun is near the horizon,an observer on a high mountain,in a balloon or in a plane may see the full circle of the rainbow.

Answer 4

Due to curvature of the earth. If u stand at a shore and look toward the ocean/sea u will find similar bow shape at the distance beyond. The rainbows form at a distance beyond our reach-- that's the reason.

Answer 5

What Are Rainbows

Answer 6

Because the earth is round the rainbows are curved 'to fit'....I guess thats how i'd explain it to primary school children =)

Answer 7

explain that if rainbows were shaped in another way other than the curved shape they always form into as we know & see them as-the poor carebears wouldn't have rainbow slippery slides to glide down or use as sliding bridges to get across one cloud to another,it'd be a catastrophic mess in the entire 'care-a-lot' community.

Answer 8

follows the curve of the earth

Answer 9

to get to the pot of gold at the end(heaven)

Answer 10

cause the sun is round